Click on your name next tot he little envelope at the top right and select account details. You then have the options menu for your account and halfway down the option to include an avatar pic
I subscribe to this site Frank and I think it allows you to use pretty much any photo for avatar. Its drag and drop (desktop to avatar box) once you have your account settings open,.
The easiest way to change your avatar is to click on your name in the upper right corner of the page. A window with options will appear. Click on "Edit" in your name, and a new window will appear that will allow you to select a new image.
In the new window, click on "Browse..." and a new window will pop up. You can navigate to the location of the image you want to use and select it.
If you want to make changes to other areas of your account, use the first step and click on "Preferences". A new window will appear with menu selections on the left.